I calculated these values by simple binary search, but I used "\p 28", which is accurate to ~14 digits, but very fast, 4 seconds for init(B);loop. Only problem is its very easy to get an overflow, so the initial starting based needs to readjusted; for n=70, I used a more complicated algorithm.

It's excellent!! Congratulations! But you are 2 weeks later. I already could calculate pentaroots but I tried to "explore" each digit by "lottery" up to 5 digits from days 15 to 17, october because I used only "kneser.gp".